Anesthesia and analgesia
-
Anesthesia and analgesia · Jul 1999
Randomized Controlled Trial Clinical TrialSmall-dose ketamine enhances morphine-induced analgesia after outpatient surgery.
Small-dose ketamine may enhance the analgesic effect of opiates. We studied the effect of IV coadministration of small-dose ketamine 50-100 microg/kg with morphine 50 microg/kg on postoperative morphine requirements and pain in 140 patients undergoing outpatient surgery. Midazolam 1-2 mg was administered in the holding area. Anesthesia was induced with propofol 2-2.5 mg/kg and was maintained with desflurane in a nitrous oxide/oxygen mixture. Patients received morphine 50 microg/kg with placebo (Group 1, n = 35) or ketamine 50 microg/kg IV (Group 2, n = 35), 75 microg/kg IV (Group 3, n = 35), or 100 microg/kg IV (Group 4, n = 35) 15 min before the end of the operation. Pain and drowsiness were assessed using visual analog scales on arrival in the recovery room, then every 15 min until the time of discharge to phase 2 recovery (phase 1 recovery). Morphine consumption in Groups 3 and 4 was approximately 40% less than that in the control group (91+/-9 and 89+/-8 microg/kg vs. 145+/-9 microg/kg; P<0.05 for both). Pain scores in Groups 3 and 4 were approximately 35% less than those in the control group at all time periods (P<0.0001 for all). There was no significant group difference in drowsiness scores. Small-dose ketamine 75-100 microg/kg IV, enhanced morphine-induced analgesia after outpatient surgery. Simultaneous use of small doses of ketamine with morphine enhances the pain relief produced by morphine. ⋯ Simultaneous use of small doses of ketamine with morphine enhances the pain relief produced by morphine.
-
Anesthesia and analgesia · Jul 1999
Randomized Controlled Trial Clinical TrialOndansetron pretreatment to alleviate pain on propofol injection: a randomized, controlled, double-blinded study.
We used a randomized, controlled, double-blinded design to study the effect of ondansetron (OND) pretreatment on the pain produced by the IV injection of propofol. Eighty patients were randomly assigned to one of two groups: Group I received 2 mL of IV 0.9% saline pretreatment, and Group II received OND (4 mg in 2 mg/mL solution) pretreatment in the dorsum of the hand, followed by propofol 1 min later. Pain was reduced significantly in the OND group (P<0.05). Approximately one third of the patients in each group had myoclonic movements or skin rashes in the limb that received propofol. We conclude that the OND pretreatment may be used to reduce the incidence of pain on injection of propofol and to prevent postoperative nausea and vomiting. ⋯ In a double-blinded, controlled study, IV ondansetron (4 mg) pretreatment was used to alleviate pain on injection of propofol. Ondansetron was successful in relieving pain without any adverse effect in a significant number of patients.
-
Anesthesia and analgesia · Jul 1999
Randomized Controlled Trial Clinical TrialThe influence of the tonsillar gag on efficacy of seal, anatomic position, airway patency, and airway protection with the flexible laryngeal mask airway: a randomized, cross-over study of fresh adult cadavers.
We conducted a randomized, controlled, cross-over cadaver study to test the hypothesis that the efficacy of seal for ventilation and airway protection, anatomic position, and airway patency with the flexible laryngeal mask airway (FLMA) are altered by the application of a Boyle Davis (B-D) gag. We also determined the airway sealing pressure (ASP) at which the FLMA prevents aspiration when large volumes of fluid are placed above the cuff. We studied 20 adult cadavers (6-24 h postmortem). Efficacy of seal for ventilation and airway protection, anatomic position, and airway patency were determined with and without a B-D gag (two blade sizes: 8 and 10 cm) for the size 3, 4, and 5 FLMA in random order. Efficacy of seal for ventilation was determined by measuring the ASP at an intracuff pressure of 60 cm H2O. Efficacy of seal for airway protection was determined by flooding the mouth with 55-135 mL of water, reducing intracuff pressure until aspiration was detected fiberoptically and measuring ASP at this intracuff pressure. Anatomic position and airway patency were determined with a fiberoptic scope at an intracuff pressure of 60 cm H2O. In addition, in vivo compliance and ASP for the FLMA were measured in 10 cadavers and 10 paralyzed, anesthetized patients. Efficacy of seal for ventilation and airway protection, anatomic position, and airway patency did not change with the application of a gag for any mask size. The mean (range) ASP at which aspiration occurred when large volumes of fluid were placed above the cuff was 11 (7-15) cm H2O. The ASP for ventilation was always higher than the ASP for airway protection (P<0.0001). The FLMA had similar in vivo compliance and ASP in cadavers and anesthetized patients. We conclude that efficacy of seal for ventilation and airway protection, anatomic position and airway patency for the FLMA are unaffected by the application of a B-D gag in adults. ASP should be >15 cm H2O if there is a maximal risk of aspiration from above the cuff. ⋯ The flexible laryngeal mask airway forms an effective seal for ventilation and protection of the airway that is unaffected by the application of a mouth gag that provides surgical access to the oropharynx. The efficacy of the seal should be >15 cm H2O if there is a maximal risk of aspiration from above the cuff.
-
Anesthesia and analgesia · Jul 1999
Randomized Controlled Trial Clinical TrialThe effects of clonidine premedication on sevoflurane requirements and anesthetic induction time.
We assessed the effects of oral clonidine preanesthetic medication (4.5 microg/kg) on the vital capacity rapid-inhalation anesthetic induction time (VCRII time) and minimum alveolar anesthetic concentration (MAC) to prevent a response to a verbal command in 50% of patients (MAC-Awake) by its hypnotic effect, and on MAC-Skin incision for the analgesic effect in patients anesthetized with sevoflurane. We studied 104 adult patients (control group: n = 52, clonidine group: n = 52) aged 30-48 yr scheduled to undergo general anesthesia. Fifty-two patients received oral clonidine 4.5 microg/kg 1.5 h before arrival in the operating room (clonidine group). The patients exhaled to residual volume and took three vital capacity breaths of 5% sevoflurane in oxygen. The VCRII time was defined as the time interval between the initiation of the VCRII and the disappearance of the response to verbal command. Anesthesia was maintained with sevoflurane in oxygen and air. The end-tidal (ET) sevoflurane concentration reached a predetermined value, then the ratio of predetermined ET to inspiratory concentration was maintained at > or =0.95 for at least 15 min before skin incision. After skin incision, the patients were observed for gross purposeful muscular movements. MAC was defined as the average of the cross-over midpoints in each cross-over. After maintaining the ET sevoflurane concentration for 15 min, patients were judged to be awake or asleep. Average times for VCRII using 5% sevoflurane were achieved in 44+/-11 s (mean +/- SD) and 27+/-6 s in the control and clonidine groups, respectively (P = 0.0001). MAC-Awake values of sevoflurane were 0.66%+/-0.03% and 0.35%+/-0.02% (P = 0.0001), and MAC-Skin incision values were 1.97%+/-0.19% and 1.29%+/-0.13% (P = 0.0001) in the control and clonidine groups, respectively. These results suggest that clonidine may have a more potent hypnotic effect than analgesic effect. ⋯ Oral clonidine preanesthetic medication (4.5 microg/kg) significantly reduces vital capacity rapid inhalation anesthetic induction time and minimum alveolar anesthetic concentration awake for sevoflurane.
-
Anesthesia and analgesia · Jul 1999
Randomized Controlled Trial Clinical TrialRopivacaine epidural anesthesia and analgesia versus general anesthesia and intravenous patient-controlled analgesia with morphine in the perioperative management of hip replacement. Ropivacaine Hip Replacement Multicenter Study Group.
The aim of our study was to compare epidural anesthesia and analgesia (EDA) with ropivacaine versus general anesthesia followed by IV patient-controlled analgesia with morphine (GA/PCA) after hip replacement regarding pain, side effects, and discharge from the postanesthesia care unit. After ethics committee approval, randomization, and informed consent, 90 patients were enrolled. In Group EDA, epidural anesthesia (ropivacaine 10 mg/mL, 15-25 mL) was followed by an epidural infusion (2 mg/mL, 4-6 mL/h for 24 h, plus top-up doses of 6-10 mL for 48 h). GA/PCA patients received general anesthesia (isoflurane/N2O/fentanyl) followed by IV patient-controlled analgesia with morphine postoperatively. Pain was assessed by using visual analog scales (0-100 mm) at rest and during physiotherapy. Pain at rest was less in the EDA (n = 43) group than in the GA/PCA (n = 45) group (at 10 h: 11.8+/-12.9 vs. 28.4+/-17.1 [P< 0.001]; at 24 h: 14.3+/-11.7 vs. 24.0+/-17 [P<0.01]; in 48 h: 14.3+/-9.3 vs. 21.1+/-17.4 [P = 0.1]). Whereas EDA patients were deemed ready for discharge from the postanesthesia care unit earlier than GA/PCA patients (5.6+/-8.9 vs. 39.7+/-41.5 min), the actual discharge time was comparable. The median time for first passage of flatus was shorter in the EDA group than in the GA/PCA group (26 vs. 47 h). Nausea and vomiting were more common in the GA/PCA group than in the EDA group (16% vs. 28% and 11% vs. 22%, respectively), whereas hypotension (11% vs. 4%) and bradycardia (14% vs. 2%) were less frequent. Under the conditions of the present study, EDA with ropivacaine provided pain control after hip replacement superior to that provided by IV patient-controlled analgesia with morphine, particularly during the first 24 h. Both approaches to pain management were equally safe. ⋯ Compared with general anesthesia and postoperative IV patient-controlled analgesia with morphine, epidural anesthesia and analgesia with the new local anesthetic ropivacaine enables patients to be discharged sooner from a postanesthesia care unit and provides superior pain relief during the first 24 h after hip replacement.